Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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680 FXUS63 KDLH 051726 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 1226 PM CDT Fri Jul 5 2024 .KEY MESSAGES... - Light to moderate rain over northwest Wisconsin will taper off this morning. Additional amounts of up to an inch are expected. - Isolated to scattered showers and a few storms are forecast this afternoon, mainly over Minnesota. - Another system will bring additional chances of rain this weekend. Diurnal rain and storm chances persist through much of next week. - High water persists across the Rainy River Basin and a Flood Advisory is in effect through early next week. See the summary at www.weather.gov/dlh/RainyRiverBasin for more information. && .DISCUSSION... Issued at 424 AM CDT Fri Jul 5 2024 Early this morning an area of light to moderate rain, with a few embedded thunderstorms, arced from southwest Minnesota through central Minnesota and into northwest Wisconsin and upper Michigan. RAP analysis revealed a stacked low was found over southeast Minnesota and southern Wisconsin with the surface low centered over southern Wisconsin. GOES-East WV and IR imagery indicated the upper-level portion of the system tightly wound with a wedge of dry air over northeast Iowa and much of Wisconsin. Model guidance has struggled to handle the evolution of this system over the past several hours and is too quick to end precipitation and push the area of low pressure to the east. Have slowed the departure of the system in the forecast by several hours this morning and hold onto PoPs several hours longer than the deterministic guidance would indicate. Cloud tops continue to gradually cool over northwest Wisconsin, although a slight warming trend has emerged in the past half hour or so. All indications are for precipitation to gradually diminish as the low pressure slips to the east-southeast this morning. There are still periodic brief thunderstorms embedded in the stratiform precipitation and think the potential for additional brief storms will persist through the morning. There remains a possibility for locally heavy rainfall due to slow storm motions and a deep warm cloud layer. The heaviest rainfall since Thursday afternoon has fallen in areas without automated gauges. Therefore we`re relying on KDLH Dual-Pol Storm Total Accumulation and MRMS-Radar Only precip estimates this morning, which reveal a stripe of 0.5 to over 4 inches of rain since Thursday morning from southern Cass to northern Pine County. Rainfall amounts over northwest Wisconsin have ticked upward over the past six hours and are now generally in the few tenths to nearly 2 inches. The few spotter reports we received seem to match up well to the radar estimates. Flood Advisories are in effect from southern Cass County to northern Pine County and we received a few reports of minor flooding. Think the water levels are likely decreasing over the advisory areas and we will be able to let those headlines expire by 14Z. Attention then shifts to this afternoon. Partial sunshine over northern Minnesota, along with weak cold air advection and cyclonic flow aloft, will support isolated to scattered showers and a few thunderstorms this afternoon and early evening. Latest CAM guidance keeps the precipitation limited to Minnesota, although a few showers may slip into the St. Croix River Valley this evening before diminishing. Temperatures today will vary with north-central Minnesota seeing upper 70s and north-central Wisconsin only in the upper 60s. A shortwave trough is forecast to propagate eastward across the Northland on Saturday. Relatively cool air aloft will support another round of diurnal showers and thunderstorms during the late morning through evening. MLCAPE values are forecast in the 500-1000 J/kg range although deep layer shear will be very weak, less than 20 knots. Showers and storms should develop and collapse over a short time period. Subsequent outflow boundaries will become the main mechanism for sustained convection through the afternoon. Small hail is not out of the question with any sustained storms. Diurnal shower and storm chances will be the norm through most of next week. Models are trending toward a dry day or two perhaps Wednesday and/or Thursday. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1225 PM CDT Fri Jul 5 2024 VFR conditions this afternoon will be speckled by scattered showers and isolated storms, for which I have included some VCSH groups for the afternoon hours. They will be capable of producing brief periods of MVFR conditions, but confidence in any actually affecting a terminal is low. Fog will be the main concern tonight, with recent rainfall, light winds and mostly clear skies all contributing. Am fairly confident in IFR visibilities affecting KDLH, KHIB, KHYR and KBRD overnight for several hours, with visibilities improving back to VFR by 13z. Scattered showers and storms are expected to develop once again Saturday afternoon, but should only affect KBRD and KHIB before 18z. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 424 AM CDT Fri Jul 5 2024 Northeast winds of 5 to 10 knots were reported over western Lake Superior this morning. An area of surface low pressure was centered over southern Wisconsin and will move east- southeastward today allowing the pressure gradient over the lake to relax and wind speeds to gradually diminish. Winds will back northerly by this afternoon and southwesterly overnight. Wind speeds will remain relatively light, in the 5 to 15 knot range, through the weekend. Aside from a small risk of a few thunderstorms, no hazardous weather is expected. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .HYDROLOGY... Issued at 119 AM CDT Fri Jul 5 2024 No updates with this issuance... Previous discussion below. A Flood Advisory remains in effect across portions of the Rainy River Basin, extending as far east as Lac La Croix and as far west as the Rainy Lake outlet. Lingering high water from June and early July rainfall continues to flow slowly through the Rainy River Basin. Headwaters gauges on the Kawishiwi River, Basswood River, and Lake Vermilion have crested and indicate that the flood wave or peak water levels are slowly making their way through the basin. However, rises continue on the Vermilion River and Lac La Croix and downstream of those points. This has led to high water and some minor flooding on Crane Lake and Namakan/Kabetogama (Nam/Kab) lakes, as well as lake levels increasing on Rainy Lake. Per the latest IJC water level bulletin, dam operators have pulled all logs at Kettle and Squirrel Falls, and continue pulling logs at International Falls as conditions allow in order to maximize outflow through the basin. However, the sheer volume of water moving through the basin will still result in rises on these lakes due to the natural constriction of the flow. Vermilion River is forecast to crest late this week and then begin slow recessions. Water level rises further downstream on Nam/Kab are likely to continue (recent rates of rise have been an inch or two a day, this is likely greatest rates of rise and should begin to slow by the weekend), with peak water level early to mid next week. As is usual for this basin, water will move slowly and recessions will happen at glacial speeds. Additional rainfall may cause brief rises in tributaries and extend the period of high water in core lakes. Boaters should expect high water, potentially hidden underwater hazards, and strong currents in constricted areas. The Flood Advisory currently extends through next Wednesday, but may need to be extended based on observed conditions. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. MARINE...None. && $$ DISCUSSION...Huyck AVIATION...LE MARINE...Huyck HYDROLOGY...Huyck/Levens